"""Voice transcription helpers for co-creation sessions."""

from __future__ import annotations

from dataclasses import dataclass
from io import BytesIO

from fastapi import HTTPException
from openai import AsyncOpenAI

from app.core.config import settings
from app.core.logging import get_logger

logger = get_logger(__name__)


@dataclass(frozen=True)
class VoiceTranscriptionResult:
    """Normalized transcription result for one uploaded voice turn."""

    transcript_text: str
    confidence: float | None = None
    provider: str = "demo"


def _normalize_transcript(transcript_text: str) -> str:
    return transcript_text.strip()


async def _transcribe_demo(
    *,
    audio_bytes: bytes,
    mime_type: str | None,
    transcript_hint: str | None,
) -> VoiceTranscriptionResult:
    hint = _normalize_transcript(transcript_hint or "")
    if hint:
        return VoiceTranscriptionResult(
            transcript_text=hint,
            confidence=1.0,
            provider="demo",
        )

    if mime_type and mime_type.startswith("text/"):
        text = _normalize_transcript(audio_bytes.decode("utf-8", errors="ignore"))
        if text:
            return VoiceTranscriptionResult(
                transcript_text=text,
                confidence=1.0,
                provider="demo",
            )

    raise HTTPException(
        status_code=503,
        detail=(
            "当前环境未配置真实语音转写，请先使用文本共创模式，"
            "或在开发模式下提供 transcript_hint。"
        ),
    )


async def _transcribe_openai(
    *,
    audio_bytes: bytes,
    file_name: str,
    mime_type: str | None,
    transcript_hint: str | None,
) -> VoiceTranscriptionResult:
    if not settings.openai_api_key:
        raise HTTPException(
            status_code=503,
            detail="OPENAI_API_KEY 未配置，无法使用 OpenAI 语音转写。",
        )

    client = AsyncOpenAI(api_key=settings.openai_api_key)
    audio_file = BytesIO(audio_bytes)
    audio_file.name = file_name

    prompt = transcript_hint.strip() if transcript_hint else None

    try:
        response = await client.audio.transcriptions.create(
            model=settings.voice_transcription_model,
            file=audio_file,
            language=settings.voice_transcription_language,
            prompt=prompt,
        )
    except Exception as exc:
        logger.warning("voice_transcription_openai_failed", error=str(exc))
        raise HTTPException(
            status_code=503,
            detail="语音转写服务暂时不可用，请稍后重试。",
        ) from exc

    transcript_text = _normalize_transcript(getattr(response, "text", "") or "")
    if not transcript_text:
        raise HTTPException(status_code=502, detail="语音转写结果为空，请重试。")

    return VoiceTranscriptionResult(
        transcript_text=transcript_text,
        confidence=None,
        provider="openai",
    )


async def transcribe_voice_audio(
    *,
    audio_bytes: bytes,
    file_name: str,
    mime_type: str | None,
    transcript_hint: str | None = None,
) -> VoiceTranscriptionResult:
    """Transcribe one uploaded audio turn according to the configured mode."""

    mode = (settings.voice_transcription_mode or "demo").strip().lower()

    if mode == "disabled":
        raise HTTPException(
            status_code=503,
            detail="当前环境已禁用语音转写，请先使用文本共创模式。",
        )
    if mode == "openai":
        return await _transcribe_openai(
            audio_bytes=audio_bytes,
            file_name=file_name,
            mime_type=mime_type,
            transcript_hint=transcript_hint,
        )

    return await _transcribe_demo(
        audio_bytes=audio_bytes,
        mime_type=mime_type,
        transcript_hint=transcript_hint,
    )